The objectives of this study are a) to obtain a pregnant baboon/Rhesus monkey preparation with fetal catheters and transducers in place which will survive in a nonlabor situation postoperatively for several days and b) to determine if prostaglandin inhibitors or beta-mimetic agents are necessary to obtain such a preparation. Pregnant animals near term will undergo laparotomy and transducers and catheters will be placed in the fetus. Use of labor inhibiting agents will be administered as necessary by the presence of uterine contractions. During recovery, the animal will be placed in a specifically designed restraining chair and vital signs will be monitored. When these objectives are obtained, it will then be possible to study the interdependence of fetal and maternal endocrine relationships without the adverse effects of acute stress secondary to anesthesia and surgery.